Antineoplastic Agents 293. The Exceptional Human Cancer Cell Growth Inhibitors Spongistatins 6 and 7

A twenty year investigation of the South African marine sponge Spirastrella spinispirulifera (Carter, 1879) for antineoplastic constituents has now led to discovery of spongistatin 6 (1e) and 7 (2b) in 3.5 × 10−7% and 2.2 × 10−7% yields. Structural elucidations were based on detailed analyses of high field (400 and 500 MHz) 2D-NMR and high resolution mass spectra. Spongistatins 6 and 7 were exceptionally potent against a subset of human cancer cell lines in the NCI screening panel which are characteristically sensitive to cellular microtubule interactive antimitotics.